Resin-coated metal sheet with higher vivid reflectivity having the excellent workable adhesion strength

ABSTRACT

In a resin-coated metal sheet, at least one surface of a metal sheet  10  as a base sheet is overlaid by a transparent polyester resin film A of 5 to 100 μm thickness through a paint layer E, a modified olefin resin layer D of 5 to 100 μm thickness, a pattern or/and solid printing layer C and an adhesive layer B which layers are put one over another in order from the side of the metal sheet toward the transparent polyester resin film. Since the modified olefin resin layer which is provided in between the transparent polyester resin film and the metal sheet has the excellent adhesiveness against the printing layer, the paint layer and the polyester resin film, even if the resin-coated metal sheet is formed under the severe condition against the resin-coated metal sheet, for instance, by deep drawing, delamination does not occur so that the excellent workable adhesion strength is shown. Further, the roughness of the surface of the metal sheet, and unevenness of several component resin layers are absorbed by a modified olefin resin layer so that the excellent vivid relectivity for a resin-coated metal sheet can be obtained.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a resin-coated metal sheet with highervivid reflectivity having the excellent workable adhesion strength, inparticular, to a resin-coated metal sheet with higher vividrefelectivity having the excellent workable adhesion strength in whicheven if the resin-coated metal sheet is formed under the severecondition against the resin-coated metal sheet, for instance, bystretch-forming of the resin-coated metal sheet or by deep-drawingthereof, delamination does not occur so that the excellent workableadhesion strength is shown.

(2) Description of the Prior Art

Recently, decorative design of higher grade is being pursued, togetherwith the grade of articles such as domestic electrical machinery andapparatus, audio, kitchen appliance, and interior finish materials beingmade higher. Decorative design of higher grade is expressed by thedecorativeness of the surface of packing materials, in particular, thehigher vivid reflectivity. Further, decorative design can be expressedby the shape of package which is formed by stretch-forming of theresin-coated metal sheet or by deep-drawing thereof. Accordingly, therequirement for a decorative steel sheet with higher vivid reflectivityhaving the workable adhesion strength fit for stretch-forming of theresin-coated metal sheet or by deep-drawing thereof is increasing.

In order to satisfy the requirement, various researches were made. Forinstance, there was proposed a method of laminating a colored metalsheet with a transparent thermosetting resin film or thermoplastic resinfilm of 5 to 100 μm and a thermoplastic resin film of 5 to 50 μmthickness having H to 7B hardness as disclosed in Japanese PatentPublication (Kokai) 55126 of 1991 (Heisei 2).

The vivid refelectivity can be obtained by the above-mentioned method.However, since delamination occurs in the interface between two resincomponent layers or the interface between laminated resin layer andcolored metal sheet, the workable shape of the decorative metal sheet islimited.

Namely, in the prior art, it was extermely difficult to obtain alaminated metal sheet which has the workability fit for stretch-formingof the resin-coated metal sheet or by deep-drawing thereof and besidesthe vivid reflectivity.

It is an object of the present invention to provide a resin-coated metalsheet which has the workable adhesion strength fit for stretch-formingof the resin-coated metal sheet or by deep-drawing thereof, and theexcellent vivid reflectivity.

DISCLOSURE OF THE INVENTION

A resin-coated metal sheet of the present invention comprises a metalsheet as a base sheet of which at least one surface is overlaid insequential order from the base sheet side with a paint layer, a modifiedpolyolefin resin layer of 5 to 100 μm thickness, a printed and/or solidcolored print layer, namely a decorative layer, an adhesive layer and atransparent polyester resin film of 5 to 100 μm thickness.

Further, a resin-coated metal sheet of the present invention comprises ametal sheet as a base sheet of which at least one surface is overlaid insequential order from the base sheet side with a paint layer, adecorative layer, a modified polyolefin resin layer of 5 to 100 μmthickness, an adhesive layer, and a transparent polyester resin film of5 to 100 μm thickness.

Furthermore, a resin-coated metal sheet of the present inventioncomprises a metal sheet as a base sheet of which at least one surface isoverlaid in sequential order from the base sheet side with a paintlayer, a modified polyolefin resin layer of 5 to 100 μm thickness, anadhesive layer, and a transparent polyester resin film of 5 to 100 μmthickness.

In these resin-coated metal sheets of the present invention, the paintlayer is preferably formed as a top coat layer of the transparentpolyester resin film.

Further, in these resin-coated metal sheets of the present invention,the adhesive layer and/or the decorative layer desirably includesaluminium pigment or mica pigment.

[Action and Effect]

Since the modified polyolefin resin layer which is provided in betweenthe transparent polyester resin film and the metal sheet has theexcellent adhesiveness against the printing layer, the paint layer andthe polyester resin film, even if the resin-coated metal sheet is formedunder the severe condition against the resin-coated metal sheet, forinstance by deep drawing, delamination does not occur so that theexcellent workable adhesion strength is shown. Further, the roughness ofthe surface of the metal sheet, and unevenness of several componentlayers (resin layers) are absorbed by a modified polyolefin resin layerso that the excellent vivid reflectivity for a resin-coated metal sheetcan be obtained.

Further, since the paint layer is formed as the top coat layer (what iscalled “top coat”or protective top layer) of the transparent polyesterresin film, scratch resistance of the resin-coated metal sheet requiredwhen the resin-coated metal sheet is formed or handled can be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 to 3 are sectional views showing the structure of one side of aresin-coated metal sheet according to the present invention.

PREFERRED EMBODIMENT

Then, embodiments of the present invention are explained in detailbelow.

FIGS. 1 to 3 show the structures of one side of resin-coated metalsheets having resin coating layers formed on a metal sheet,respectively.

In the present invention, resin coating layers may be provided on bothsides of a metal sheet, or only on one side of a metal sheet.

Then, the first embodiment of the present invention is explained inwhich resin coating layers are provided on one side of a metal sheet.

FIG. 1 corresponds to a resin-coated metal sheet in which “A” denotes atransparent polyester resin film, “B” denotes an adhesive layer, “C” adenotes decorative layer, “D” denotes a modified olefin resin layer, “E”denotes a paint layer, and “10” denotes the metal sheet.

In the embodiment of the present invention shown in FIG. 1, transparentpolyester resin film A is 5 to 100 μm thick, which forms the outsidelayer of the resin-coated metal sheet. The thickness of transparentpolyester resin film A is preferably 15 μm to 80 μm. When the thicknessof transparent polyester resin film A is less than 5 μm, vividreflectivity of the whole of the resin-coated metal sheet is inferior,and besides handling of transparent polyolefin resin film A inlaminating is difficult. When the thickness of transparent polyesterresin film A is more than 100 μm, the workable adhesion strength of theresin-coated metal sheet is inferior.

In order to improve scratch resistance of the resin-coated metal sheetin forming it or in handling it, transparent polyester resin film A ispreferably coated with a top coat of thermosetting paint or ultravioletirradiated resin paint such as silicone resin paint, fluoride resinpaint, acrylic resin paint, melamine resin paint or urethane resin paintof 0.2 μm to 50 μm thickness, in which the thickness of the top coat ismore preferably 0.5 μm to 30 μm. When the thickness of the top coat isless than 0.2 μm, the interference color is noticeably seen, and besidescut resistance is inferior. On the other hand, when the thickness of thetop coat is more than 50 μm, the workability thereof decreases, andbesides the economical efficiency is inferior.

Transparent polyester resin film A includes polyethylene terephthalateresin (PET) and copolymer thereof PET is a thermoplastic.

Adhesive layer B contains resin such as polyester resin, epoxy resin,acrylic resin, melamine resin or urethane resin.

Further, adhesive assistant having the adhesive effect such asγ-glycidoxypropyl trimethoxysilane (for instance, silane coupling agentmade by Nippon Unicar Co., Ltd.) can be used as ingredient in additionto the above-mentioned resin. The thickness of adhesive layer B ispreferably 0.1 μm to 50 μm, more preferably 0.5 μm to 30 μm. When thethickness of adhesive layer B is less than 0.1 μm, the boiling waterresistance and the workable adhesion strength of the resin-coated metalsheet are inferior. On the other hand, when the thickness of theadhesive layer is more than 50 μm, disfiguring the external appearanceof resin-coated metal sheet is caused by residual solvent which adhesivehas when the laminate film is heated for laminating. Thereby, the vividreflectivity of resin-coated metal sheet becomes inferior.

Adhesive layer B can contain pigment such as aluminium powder or micapowder too. In this case, the ratio of aluminium pigment to solid matterin adhesive is preferably 0.1% by weight to 30% by weight, moredesirably 1% by weight to 20% by weight, because when the ratio ofaluminium pigment to solid matter in adhesive is less than 0.1% byweight, metallic luster cannot be given, and when the ratio of aluminiumpigment to solid matter in adhesive is more than 30% by weight, theadhesive layer becomes fragile and besides the vivid reflectivity ofresin-coated metal sheet becomes inferior.

The particle of aluminium pigment has globelike shape or scalelikeshape. The average particle size thereof is preferably 0.1 μm to 100 μm,more desirably 1 μm to 80 μm, in either globelike particles or scalelikeparticles, because when the average particle size is less than 0.1 μm,the decorativeness of resin-coated metal sheet is worsened, and when theaverage particle size is more than 100 μm, the vivid reflectivity ofresin-coated metal sheet becomes bad.

The ratio of mica pigment to solid matter in adhesive is preferablyabout 0.1% by weight to 30% by weight, more desirably 1% by weight to20% by weight, because when the ratio of mica pigment to solid matter inadhesive is less than 0.1% by weight, the metallic luster cannot begiven, and when the ratio of mica pigment to solid matter in adhesive ismore than 30% by weight, the adhesive layer becomes fragile.

The particle of mica pigment has globelike shape or scalelike shape. Theaverage particle size thereof is preferably 0.1 μm to 100 μm, morepreferably 1 μm to 80 μm, in either globelike particles or scalelikeparticles, because when the average particle size is less than 0.1 μm,the decorativeness of resin-coated metal sheet is worsened, and when theaverage particle size is more than 100 μm, the vivid reflectivity ofresin-coated metal sheet is worsened.

Then, pattern or/and solid decorative layer C comprises a patternprinting layer and/or solid printing layer for giving the decorativenessto a resin-coated metal sheet. Resin for pattern or/and solid printinglayer C includes polyester resin, epoxy resin, acrylic resin, melamineresin or urethane resin.

Polyester resin is particularly preferable, since when polyester resinis used, the workable adhesion strength of the resin-coated metal sheetis higher.

When the decorative layer is a pattern printing layer, the thickness ofdecorative layer is preferably 1 μm to 5 μm, because when the thicknessof decorative layer is less than 1 μm, a printing pattern cannot comeout well, and when the thickness of decorative layer is more than 5 μm,solvent of printing ink remains in the decorative layer C by whichvariations in the vivid reflectivity of resin-coated metal sheet aregenerated.

When the decorative layer C is a solid printing colored layer, thethickness of the decorative layer is preferably 1 μm to 5 μm, becausewhen the thickness of the decorative layer is less than 1 μm, variationsin coloring tone of the decorative layer are generated, and when thethickness of the decorative layer is more than 5 μm, variations in thevivid reflectivity of resin-coated metal sheet are generated, andbesides it is not economical.

The printing layer can contain aluminium pigment or mica pigment too, inwhich the ratio of pigment to solid matter in printing ink is preferably0.1% by weight to 30% by weight, more desirably 1% by weight to 20% byweight, in the same manner as the above-mentioned ratio of pigment tosolid matter in the adhesive layer.

Modified polyolefin resin layer D is 5 μm to 100 μm thick, which is theessential element of the present invention for giving the excellentworkable adhesion strength and the high vivid reflectivity to theresin-coated metal sheet.

The modified polyolefin resin is produced by blending propylenecopolymer having a carboxyl group within a molecule with polypropylenein the following ratio: polypropylene copolymer 100 parts by weight to20 parts by weight, and polypropylene 100 parts by weight to 0 parts byweight.

The thickness of modified polyolefin resin layer D is preferably 10 μmto 80 μm, more preferably 20 μm to 70 μm. When the thickness of modifiedpolyolefin resin layer D is less than 5 μm, the vivid reflectivity ofthe whole of resin-coated metal sheet is lowered, and when the thicknessof modified polyolefin resin layer D is more than 100 μm, the surfacehardness and the workable adhesion strength of the whole of resin-coatedmetal sheet is lowered.

The modified polyolefin resin includes polyolefin polymer having atleast one functional group selected from the group consisting ofhydroxyl group, hydrolyzable group, carboxyl group, and acid anhydrousgroup within the molecule, or a mixture of the polyolefin polymer withother polyolefin polymer.

One or more kinds of pigment may be mixed in the modified polyolefinresin layer.

Further, it is preferable to apply an anchor coat on an upper side or abottom side or both sides of the modified polyolefin resin layer byusing silane coupling agent and others in order to improve adhesivestrength of between resin layers.

The above mentioned transparent polyester resin film A, adhesive layerB, printing layer C and modified polyolefin resin layer D are totallycalled a “Laminate film”

Paint layer E shown in FIG. 1 is provided for forming a color layerwhich is directly formed on a metal sheet as a design. Resin for paintincludes polyester resin, acrylic resin, urethane resin, epoxy resin ormelamine resin as chief ingredients. It is preferable that polyesterresin is used as chief ingredients in particular, because the workableadhesion strength is extremely good. The thickness of the paint layer ispreferably 1 μm to 50 μm, more preferably 5 μm to 30 μm.

Further, paint layer E includes a paint layer formed of two or morelayers. Namely, the paint layer E may include a laminate formed ofplural layers having an under coating including rust preventing pigment.For instance, a first layer as an under coating layer may be formed ofcolor paint, and a second layer laid on the under coating layer may beformed of clear paint. The metal sheet 10 as a base sheet shown in FIG.1 includes steel sheets, stainless steel sheet, and surface treatedsteel sheets such as galvanized sheet iron, composite galvanized sheetiron, nickel-plated steel sheet and tin-free steel. Further the metalsheet 10 may include nonferrous metal sheets such as aluminium sheet andcopper sheet.

The thickness of the metal sheet 10 is preferably 0.2 mm to 1.2 mm.

When one side of the metal sheet 10 is coated with resin, a bottom layerof the metal sheet 10 (namely, a side of the metal sheet 10 which is notcoated with resin) is favorably coated with rust proofing paint of 0.1μm to 50 μm thickness, and further the bottom layer is preferably coatedwith polyvinyl chloride for rust proofing. Paint resin including, as aprincipal component, resin such as polyester resin, acrylic resin,polyurethane resin, epoxy resin, or melamine resin is suitable.

FIG. 2 corresponds to an invention wherein “A” is a transparentpolyester resin film, “B” is an adhesive layer, “C” is a pattern or/andsolid printing layer, “D” is a modified olefin resin layer, “E” is apaint layer, and “10” is the metal sheet. This embodiment differs fromthe first embodiment shown in

FIG. 1 in that pattern or/and solid decorative layer C and modifiedpolyolefin resin layer D are exchanged with each other in an order oflaminating.

Namely, in the resin-coated metal sheet as described shown in FIG. 2,decorative layer C is formed between paint layer E and modifiedpolyolefin resin layer D. In this case, transparent modified polyolefinresin layer is used as modified polyolefin resin layer D so as to givevivid reflectivity to a design of decorative layer C formed thereunderso that pattern of decorative layer C can be seen from outside.

FIG. 3 corresponds to an invention, in which “A” is a transparentpolyester resin film, “B” is an adhesive layer, “C” is a modified olefinresin layer, “D” is a paint layer, and “10” is the metal sheet.

This embodiment differs from the second embodiment of FIG. 2 in thatdecorative layer C does not exist in the laminate film. In this case,the appearance of paint layer D can be observed from above oftransparent polyester resin film A.

A Method of Producing a Resin-coated Metal Sheet

(1) Production of painted steel sheet

Coating of galvanized sheet iron with resin paint is made by rollcoating one time or two times, in which when the thickness of paintlayer is needed to be increased, further times of painting is increased.

(2) Production of a laminate film

An instance of production of a laminate film shown in FIG. 1 isexplained below.

First, adhesive is painted on polyester resin film by roll coating toform an adhesive layer on the polyester film. After drying, a pattern isprinted on the adhesive layer. Further according to demand, solidprinting is made thereon. Or there is a case where pattern printing isomitted and only solid printing is made. Modified polypropylene resinlayer is formed over the printing layer by extrusion coating to form alaminate film.

(3) Overlay

After the painted steel sheet was heated, the painted steel sheet isoverlaid by the laminate film by means of laminating roll, and then thepainted steel sheet overlaid by a laminate film is further heated, andpressed by means of a mirror roll. Thereafter the painted steel sheetoverlaid by the laminate film is cooled. In this time, the suitable rollpressure of the laminating roll is 1 kg/cm² to 80 kg/cm², and moredesirably 5 kg/cm² to 60 kg/cm². When the roll pressure is less than 1kg/cm², the laminate film cannot be brought into close contact with thepainted steel sheet uniformly over the width of the painted steel sheetso that the variations in the apprearance (vivid reflectivity) can befound. On the other hand, when the roll pressure is more than 80 kg/cm²,the abrasion of the roll occurs heavily so that the exchange oflaminating roll should be made frequently, therefore, the productivitybeing decreased.

EXAMPLE 1

(Production of Painted Steel Sheet)

Polyester copolymer paint including white pigment was painted onGalvanized sheet iron having 0.5 mm thickness, 10 g/m² galvanizingamount, 0.05 mg/dm² chromate film layer (as amount of chromium) andaverage surface roughness Ra of 0.3 μm, with thickness 15 μm and madethermoset to form a painted steel sheet.

(Production of a Laminate Film)

Polyester resin adhesive was painted on a transparent polyethyleneterephthalate film of 25 μm thickness which was previousely top-coatedwith polyester resin of 5 μm thickness (film-protective layer), withthickness 1 μm, and then a grain pattern was printed thereon by usingpolyester resin ink, with thickness 1 μm. Thereafter, transparentmodified polypropylene resin layer (consisting of a mixture of 100 partsby weight of polypropylene copolymer with 100 parts by weight ofpolypropylene) of 20 μm thickness was formed on the printed side of thepolyethylene terephthalate film by extrusion coating to form a laminatefilm.

(Overlay)

The painted steel sheet was overlaid by the laminate film in anatmosphere of 200° C., under the roll pressure of 20 kg/cm².

As a result, the numerical value indicating the vivid reflectivity ofthe resin-coated metal sheet was 0.8 and good, and workable adhesionstrength thereof was excellent.

Comparative Example 1

A painted steel sheet was produced in the same manner as in Example 1,and then overlaid by the following laminate film. Namely, polyesterresin adhesive was painted on transparent polyethylene terephthalatefilm of 25 μm thickness, with thickess 1 μm, and then a grain patternwas printed on the adhesive layer, with thickness 1 μm by usingpolyester resin ink to form a laminate film.

Then, the painted steel sheet was overlaid by the laminate film to forma resin-coated metal sheet in the same manner as in Example 1. As aresult, the workable adhesion strength of the resin-coated metal sheetwas good, however the numerical value indicating the vivid reflectivitythereof was 0.1, bad and poor.

EXAMPLE 2

A painted steel sheet produced in the same manner as in Example 1, andthen overlaid by the following laminate film. Namely, polyester resinadhesive was painted on one side of transparent polyethyleneterephthalate film of 100 μm thickness, with thickness 5 μm. Thentransparent modified propylene resin layer of 100 μm thickness wasformed on the painted side of the polyethylene terephthalate byextrusion coating. And then the grain pattern printing and the solidpattern printing ere made in order on the modified propylene resin layerwith each thickness 5 μm by using polyester resin ink to form a laminatefilm.

Then, the painted steel sheet used in Example 1 overlaid by the laminatefilm in an atmosphere of 200° C. under the roll pressure of 20 kg/cm²,by which a resin-coated metal sheet having the vivid reflectivity wasformed. This resin-coated metal sheet had the vivid reflectivity of 1.0and the excellent workable adhesion strength.

Comparative Example 2

A painted steel sheet was produced in the same manner as in Example 1,and then overlaid by the following laminate film. Namely, polyesterresin adhesive was painted on a transparent polyethylene terephthalatefilm of 100 μm thickness, with thicness 5 μm. Then, a transparentpolypropylene resin layer of 100 μm thickness was formed on thepolyethylene terephthalate film by extrusion coating. Then the grainpattern printing and the solid printing were made in order on thepropylene resin layer, with each thickness 5 μm, by using polyesterresin ink to form a laminate film.

Then the painted steel sheet was overlaid by the laminate film in thesame manner as in Example 1 to form a resin-coated metal sheet. As aresult, the numerical value of the vivid reflectivity of theresin-coated metal sheet was 0.8 and good. However, the workableadhesion strength thereof was bad and poor.

EXAMPLE 3

A painted metal sheet was produced in the same manner as in Example 1,and then overlaid by the following film. Namely, silane coupling agentwas painted on one side of a transparent polyethylene terephthalate filmof 12 μm thickness, with thickness 0.5 μm, and then solid printing wasmade thereon by polyester resin ink including mica pigment, withthickness 4 μm. Then, transparent modified polypropylene resin layer of5 μm thickness was formed on the printed side of the polyethyleneterephthalate film by extrusion coating to form a laminate film.

Then, a painted steel sheet used in Example 1 was overlaid in anatmosphere of 200° C., under the roll pressure of 20 kg/cm² to form aresin-coated metal sheet having the vivid reflectivity. As a result, thenumerical value indicating the vivid reflectivity of the resin-coatedmetal sheet was 0.7, and the workable adhesion strength thereof wasexcellent.

Comparative Example 3

A painted steel sheet was produced in the same manner as in Example 1,and overlaid by the following laminate film. Namely, silane couplingagent was painted on one side of a transparent polyethyleneterephthalate film of 12 μm thickness, with thickness 0.5 μm. Then,solid printing was made thereon by using polyester resin ink includingmica pigment, with thickness 4 μm. Transparent propylene resin layer of5 μm thickness is formed on the printed side of the polyethyleneterephthalate film by exrusion coating to form a laminate film.

Then the painted steel sheet was overlaid by the laminate film in thesame manner as in Example 1 to form a resin-coated metal sheet. As aresult, the numerical value indicating the vivid reflectivity of theresin-coated metal sheet was 0.7, and good. However, the workableadhesion strength was bad and poor.

EXAMPLE 4

A painted steel sheet was produced in the same manner as in Example 1,and then overlaid by the following laminate film. Namely, Polyesterresin adhesive including aluminium pigment was painted on one side of atransparent polyethylene terephthalate film of 50 μm thickness, withthickness 50 μm.

Then transparent modified polypropylene resin of 50 μm thickness wasformed thereon by extrusion coating to form a laminate film.

Then, the painted steel sheet used in Example 1 was overlaid by thelaminate film in an atmosphere of 200° C., under the roll pressure of 20kg/cm² to form a resin-coated metal sheet with vivid refelectivity. Thenumerical value indicating the vivid reflectivity of the resin-coatedmetal sheet was 0.7, and the workable adhesion strength was excellent.

Comparative Example 4

A painted steel sheet was produced in the same matter as in Example 1,and then overlaid by the following laminate film. Namely. polyesterresin adhesive including aluminium pigment was painted on one side of atransparent polyethylene terephthalate film of 50 μm thickness, withthickness 50 μm. Then, a transparent polypropylene resin layer of 50 μmthickness was formed thereon by extrusion coating to form a laminatefilm.

Then, the painted steel sheet was overlaid by the laminate film in thesame manner as in Example 1 to form a resin-coated metal sheet. As aresult, the numerical value indicating the vivid reflectivity of theresin-coated metal sheet was 0.7 and good. However the workable adhesionstrength thereof was bad and poor.

(Method of Valuation)

(Vivid Reflectivity)

The vivid reflectivity of the resin-coated metal sheet of the presentinvention was measured by the following method. Namely, the vividreflectivity of reflected image, namely the vivid reflectivity of normalreflected image on decorative surface of resin-coated metal sheet wasmeasured by means of a portable distinctness of image glossmeter PGD-4type (made by Japan Color Research Institute). The higher the measuredvalue is, the higher the vivid reflectivity is.

A method of measurement was as follows. Namely, a resin-coated metalsheet of 10 cm×10 cm was pushed against the glossmeter horizontally, andscale of the glossmeter was read with naked eyes as the vividreflectivity.

(Workable Adhesion Strength)

In the present invention, valuation of workable adhesion strength wasmade by taking the following two measurements and judging the resultsthereof synthetically.

(1) Erichsen test

Checkered cuts reaching a base metal are made in a resin-coated surfaceof resin-coated metal sheet by a cutter knife, and 8 mm stretch-formingof the resin-coated metal sheet was made from the backside of theresin-coated metal sheet by Erichsen tester. Thereafter, the extent ofdelamination was valuated by heating continuousely the resin-coatedmetal sheet at 100° C. for one hour and thereafter observing theexisting of delamination. In Table No. 1, the mark “⊚” designates “nodelamination”, and the mark “X” designates “delamination”.

(2) Cup-deep drawing test

Deep drawing of a resin-coated metal sheet into a cup was made byYamada-way deep drawing tester, with drawing ratio r=2.2. Checkered cutsreaching a base metal were made in a resin surface of the resin-coatedmetal sheet formed into a cylindrical part of cup, with a space of 5 mm.Thereafter, the extent of delamination was valuated by heatingcontinuousely the resin-coated metal sheet formed into a cup by deepdrawing and thereafter observing the existing of delamination. In Table1, the mark “⊚” designates “no delamination”, and the mark “X”designates “delamination”.

Effect of the Invention

As apparent from Table 1 and 2, since modified polyolefin resin layerincluded in a laminate film has excellent adhesion strength withprinting layer, paint layer, polyester resin film and others, even ifsevere work such as deep drawing is made, delamination between layersdoes not occur. Therefore, resin-coated metal sheet of the presentinvention has the excellent workable adhesion strength. Further, sincesurface roughness and convex and concave parts of each layer (resinlayer) are absorbed by modified polyolefin resin layer, resin-coatedmetal sheet of the present invention has the excellent vividreflectivity for resin-coated metal sheet.

TABLE 1 Workable adhesion The composition of a laminate film strengthPainted steel sheet Transparent Value of Cup-deep Color paint Polyolefinresin Printing layer Adhesive polyester vivid Erichsen drawing Metalsheet layer E layer D C layer B resin film A reflectivity test testExample Galvanized sheet Polyester Transparent Polyester ink PolyesterTransparent 0.8 ⊚ ⊚ 1 iron copolymer inc. modified poly- grain printingresin polyethylene 0.5 mm thickness white pigment propylene resin 1 μm 1μm terephthalate 15 μm 20 μm film 25 μm Comparison Galvanized sheetPolyester — Polyester ink Polyester Transparent 0.1 ⊚ ⊚ 1 iron copolymerinc. grain printing resin polyethylene 0.5 mm thickness white pigment 1μm 1 μm terephthalate 15 μm film 25 μm Example Galvanized sheetPolyester Transparent Polyester ink Polyester Transparent 1.0 ⊚ ⊚ 2 ironcopolymer inc. modified poly- grain + solid resin polyethylene 1.0 mmthickness white pigment propylene resin printing 5 μm terephthalate 20μm 100 μm 10 μm film 100 μm Comparison Galvanized sheet PolyesterTransparent Polyester ink Polyester Transparent 0.8 X X 2 iron copolymerinc. polypropylene grain + solid resin polyethylene 1.0 mm thicknesswhite pigment resin 100 μm printing 5 μm terephthalate 20 μm 10 μm film100 μm Example Tin-free steel Polyester Transparent Polyester ink SilaneTransparent 0.7 ⊚ ⊚ 3 0.3 mm thickness copolymer inc. modified poly-solid printing coupling polyethylene white pigwent propylene resin inc.mica agent terephthalate 5 μm 5 μm pigment 4 μm 0.5 μm film 12 μmComparison Tin-free steel Polyester Tarnsparent Polyester ink SilaneTransparent 0.7 X X 3 0.3 mm thickness copolymer inc. polypropylenesolid printing coupling polyethylene white pigment resin 5 μm inc. micaagent terephthalate 5 μm pigment 4 μm 0.5 μm film 12 μm

TABLE 2 Workable adhesion The composition of laminate film strengthPainted steel sheet Transparent Value of Cup-deep Color paint Polyolefinresin Printing layer Adhesive polyester vivid Erichsen drawing Metalsheet layer E layer D C layer B resin film A reflectivity test testExample Stainless steel Epoxy resin inc. Modified poly- — PolyesterTransparent 0.7 ⊚ ⊚ 4 sheet light brown propylene resin resinpolyethylene 0.5 mm thickness 30 μm 50 μm inc. Al terephthalate pigmentfilm 50 μm 50 μm Comparison Stainless steel Epoxy resin inc. Transparent— Polyester Transparent 0.7 X X 4 sheet light brown polypropylene resinpolyethylene 0.5 mm thickness 30 μm 50 μm inc. Al terephthalate pigmentfilm 50 μm 50 μm

What is claimed is:
 1. A resin-coated metal sheet consisting essentiallyof a metal sheet as a base sheet of which at least one surface thereofis overlaid in sequential order from the base sheet surface with a paintlayer, a modified polyolefin resin layer of 5 to 100 μm thickness, adecorative layer, wherein said decorative layer comprises at least oneof a solid or a pattern, an adhesive layer and a transparent polyesterresin film of 5 to 100 μm thickness.
 2. A resin-coated metal sheet asclaimed in claim 1, wherein the adhesive layer includes aluminiumpigment.
 3. A resin-coated metal sheet as claimed in claim 1, whereinthe decorative layer includes aluminium pigment.
 4. A resin-coated metalsheet as claimed in claim 1, wherein the decorative layer includes micapigment.
 5. A resin-coated metal sheet as claimed in claim 1, wherein aresin coating layer is formed as a protective top coat layer of thetransparent polyester resin film.
 6. A resin-coated metal sheet asclaimed in claim 1, wherein the adhesive layer includes mica pigment. 7.The resin-coated metal sheet of claim 1, wherein said modifiedpolyolefin resin layer, said decorative layer, said adhesive layer andsaid transparent polyester resin film together comprise a laminate film.8. A resin-coated metal sheet consisting essentially of a metal sheet asa base sheet of which at least one surface thereof is overlaid insequential order from the base sheet surface with a paint layer, adecorative layer, wherein said decorative layer comprises at least oneof a solid or a pattern, a modified polyolefin resin layer of 5 to 100μm thickness, an adhesive layer, and a transparent polyester resin filmof 5 to 100 μm thickness.
 9. A resin-coated metal sheet as claimed inclaim 8, wherein a resin coating layer is formed as a protective topcoat layer of the transparent polyester resin film.
 10. A resin-coatedmetal sheet as claimed in claim 8, wherein the adhesive layer includesaluminum pigment.
 11. A resin-coated metal sheet as claimed in claim 8,wherein the paint layer includes aluminum pigment.
 12. A resin-coatedmetal sheet as claimed in claim 8, wherein the adhesive layer includesmica pigment.
 13. A resin-coated metal sheet as claimed in claim 8,wherein the decorative layer includes mica pigment.
 14. The resin-coatedmetal sheet of claim 8, wherein said decorative layer, said polyolefinresin layer, said adhesive layer and said transparent polyester resinfilm together comprise a laminate film, wherein said decorative layercomprises at least one of a solid or a pattern.